Estimation of Juvenile Hormone-titers by mass-spectrometry in adults and larval instars of T. commodus. Haemolymph-extracts will be made to determine the quantitative amount of Juvenile Hormone I, II and III in the various developmental stages of the crickets. Influence of single and multiple matings on the oviposition rate and hatching-rate in crickets. Site of action of Prostaglandin E2, which releases oviposition.